The present invention relates to certain oxadiazole derivatives and their use as corn root worm insecticides.
British Pat. No. 1,213,707 discloses insecticidal compounds of the general formula ##STR2## wherein X.sub.1 and X.sub.2, which may be the same or different, each represents an oxygen or sulfur atom; A represents an alkylene group; R.sub.1 represents an alkyl group, R.sub.2 represents an alkyl or alkoxy group; and R.sub.3 represents a hydrogen atom or an optionally substituted carbamoyl or amino group. A particular species disclosed in the British patent at Table 2, 9th compound from the top, is 3-(diethoxyphosphinothioylthiomethyl)-5-methyl-1,2,4-oxadiazole.
The examples of the British patent show testing of certain of the compounds for insecticidal activity on adult houseflies; mosquito larvae, diamond back moth larvae, aphids and adult mustard beetles; red spider mites; and white butterfly larvae. None of these tests involved application and use of the insecticide in the soil habitat of the insects.
U.S. Pat. No. 4,028,377 discloses insecticidal compounds of the general formula ##STR3## wherein R.sub.1 represents hydrogen, unsubstituted alkyl, benzyl or phenyl, R.sub.2 represents methyl or ethyl, and R.sub.3 represents unsubstituted C.sub.1 -C.sub.7 alkyl optionally interrupted by oxygen or represents C.sub.3 -C.sub.4 alkenyl.
The examples of the U.S. Pat. No. 4,028,377 show testing of certain of the compounds for insecticidal activity on ticks in cotton wool; larvae of ticks; mites; and on root-gall-nematodes in soil. In the latter test, the soil infested with the root-gall-nematocides was treated with the compounds to be tested and then tomato seedlings were planted either immediately after the soil preparation or after 8 days waiting.
British Pat. No. 1,261,158 discloses compounds of the general formula ##STR4## The first compound disclosed in Table I of British Pat. No. 1,261,158 is 5-(diethoxyphosphinothioylthiomethyl)-3-methylisoxazole. The compounds of the examples of British Pat. No. 1,261,158 were tested for insecticidal effectiveness on flies, mosquito larvae, moth larvae, mustard beetles, aphids, spider mites and butterfly larvae.
As described in the Ortho Seed Treater Manual, copyright 1976, Chevron Chemical Company, page 27, corn root worms have been controlled with chlorinated hydrocarbon insecticides, but in areas where resistance to such treatment has developed, good control has been obtained with organic phosphorus or carbamate soil insecticides such as Diazinon and Carbofuran insecticides. The chemical names and formulas for these latter insecticides is given below:
Diazinon insecticide: O,O-diethyl O-(2-isopropyl-4-methyl-6-pyrimidinyl)phosphorothioate ##STR5## Carbofuran insecticide: 3,3-dihydro-2,2-dimethyl-7-benzofuranylmethylcarbamate ##STR6##